There's the introduction of Santiago Cabrera's dashing knight-to-be in the aptly-titled 'Lancelot' and finale 'Le Morte d'Arthur', but for our money, the best installment of Merlin's freshman run was penultimate episode 'To Kill the King' - the shock death of Gwen's father (David Durham) proved that this show meant business!

Series Two Highlight - 'The Lady of the Lake'This was a tough one. Series two finale 'The Last Dragonlord' was a real contender - an action epic that saw the Great Dragon (John Hurt) reign destruction down on Camelot and Merlin (Colin Morgan) reunited with his father Balinor (John Lynch).

But we're big softies here at DS so we're going to plump for the episode that introduced Freya (Laura Donnelly), the druid girl who fell in love with Merlin, but tragically lost her life. *sniff* Is there something in our eye?

Series Three Highlight - 'The Tears of Uther Pendragon'Again, the series finale was a good 'un here - Uther (Anthony Head) finally learning the extent of his folly as Morgana seized the throne in 'The Coming of Arthur' made for great telly...

But ultimately series three's premiere 'The Tears of Uther Pendragon' wins out - it had epic battles, an undead army, smirking Katie McGrath and Anthony Head with a sword... what more do you need on a Saturday night?!

Series Four Highlight - 'Sword in the Stone'This time, the finale wins out - formidable two-parter 'Sword in the Stone' is the clear highlight in what is - to date - Merlin's strongest series. Morgana's latest scheme is defeated with the help of Tristan and Isolde - top-notch guest stars Ben Daniels and Miranda Raison - and Arthur finally wields a legendary blade...

An honourable mention though to ep 4.9 'Lancelot du Lac' which saw the slain knight return, under the thrall of Morgana, and seduce Gwen (Angel Coulby), breaking poor Arthur's heart.

Series Five Highlight - 'The Dark Tower'We realize that Merlin's fifth and final series hasn't yet completed its run and that the two-part finale - which will presumably see Arthur (Bradley James) finally learn the truth about his faithful servant - will likely be the clear highlight, but 'The Dark Tower' has easily been the strongest episode thus far...

As dark as the show's ever been and is ever likely to be, this ground-breaking installment saw Gwen suffer a psychological breakdown as she's first haunted by spooks and spectres and then suffers a devastating loss, with her brother Elyan (Adetomiwa Edun) sacrificing his life to save her - a fantastic 42 minutes.

Do you agree with our picks? Name your own favorite Merlin episodes below!